The present invention relates to a light hardening device and a light source suitable for use in a light hardening device.
A conventional light hardening device is disclosed, for example, in U.S. Pat. No. 5,420,768. This conventional device includes a plurality of light diodes mounted on a common base body. The light emitted by the light diodes is conducted to a light guide and can be used, for example, for the light hardening of suitable polymerizable masses which are deployed, for example, in the dental practice.
It is further conventionally known to provide a cooling arrangement for the base body on which the light diodes are mounted.
It has already been proposed to use a cooling body as the base body, whereby, for example, reference is made to copending U.S. patent application Ser. No. 10/023,232. In accordance with the arrangement disclosed therein, a cooling body is provided which has numerous LEDs mounted on its base surface. The cooling body is encircled by ribbed elements and the light passing therefrom is conducted to a light guide, whereby a portion of the light exits after first being reflected by the ribbed elements which are arranged in front of the light guide and configured in opposition thereto.
The just described arrangement offers a basic good cooling of the LED arrangement.
To be sure, if for the purpose of achieving a maximum light output, the base surface of the cooling body is provided with a plurality of closely adjacent LED chips, then the cooling body becomes too hot in connection with an intensive outer cooling as a consequence of which, in accordance with the heretofore described conventional arrangement, a pre-determined distance between the LED chips must be maintained. The free surface surrounded by the chips serves at the same time as a reflective surface which reflects the light again which has been reflected from the mirrored inner counter cone (which has a geometry corresponding to that of the front ribbed element body) and the light is ultimately guided to the light guide.
U.S. Pat. No. 6,123,545 shows a device for curing polymerizable dental materials. In this device a conventional halogen lamp is employed.
This conventional approach has led, surprisingly, to the circumstance that exactly at the front ribbed element body, the ribbed element body is substantially heated so that, in fact, a water cooling arrangement has been proposed. A water cooling arrangement can, indeed, substantially improve the cooling effect, but such an arrangement increases the weight of the light hardening device to an extent that the device is too heavy for suitable hand deployment.
The present invention offers a solution to the challenge of providing a light hardening device as well as a light source which improves the light working efficiency xe2x80x94that is, the relationship or ratio between the light performance given thereby and the heat or warmth given off by the device.
The arrangement of the present invention offers, surprisingly, the possibility to improve the efficiency of the device despite a reduction in the base surface which is available for receiving thereon the LED chips. By the arrangement of the LED chips on the rear surface, the light guide is disposed in direct neighboring relationship thereto and the light can be irradiated thereunto by the LED chips. The cooling body preferably expands from the rear surface outwardly towards its other end so that the mass and surface available for heat transfer is, in comparison to the cross-section of the rear surface, drastically enlarged. In accordance with the present invention, it is particularly advantageous that, through the arrangement of the LED-chips on the rear surface xe2x80x94that is, immediately neighboring the light guide xe2x80x94there is not a need to provide reflective surfaces. In the known approaches in which the LED chips are mounted on the cooling body, the light is, to a large extent, conducted onto reflective surfaces, is reflected thereby, and, after varying multiple further reflections, eventually is guided to the light guide. Evaluations in connection with the understanding of the conventional approaches have shown that the reflecting activity not only reduces the light efficiency, but also increases considerably the heat or warmth which is generated and which must then necessarily be transferred or guided away.
In accordance with the present invention, it is provided, in contrast, to directly irradiate the light guide in a reflection free manner. The heat shed or given off by the LED chips is at the same time also emitted onto the light guide so that, in accordance with the present invention, the heat radiation can be deployed for polymerizable masses as well.
In accordance with the present invention, it is provided that the multiple LED arrangement gives off heat in the manner of a xe2x80x9chotter markxe2x80x9d approach to the light hardening apparatus. Through the distribution of heat over the relatively large surface area of the conically shaped cooling body, it is ensured that the light hardening device of the present invention is, in total, not heated too severely.
Additionally, the light hardening device of the present invention, in offering a particularly high light output, makes possible a rapid true hardening of the hardenable mass. The hardening time can be reduced, for example in contrast to that of a hand deployable halogen glow lamp, by one-half. By means of the shortened hardening time, the heat capacity of the cooling body also plays a role, on the other hand, to effect a reduction in the temperature level. This means, in practical use, that during the hardening time the increase in temperature exteriorly of the light hardening device is not noticeable and that the cooling apparatus undertakes, as well, a cooling function following the conclusion of the hardening process so that the temperature, when regarded over time, is graduated or smoothed.
In accordance with the present invention, it is nonetheless particularly advantageous that the LED arrangement in combination with the cooling body can be deployed, as well, in substitution for the reflecting halogen glow lamp of a hand deployed light hardening device. The device of the present invention permits a substantial increase in the light performance or output and the life or length of operation of the device and, thereby, as well, the reliability of the light hardening device is automatically increased. It is now possible to avoid the heretofore problematic hardening process which could be interrupted by the burning through of a glow lamp creating a situation in which patients having a partially hardened filling or the like have had to wait. Heretofore, in order to avoid such unfavorable situations in which a further hardening of a partially hardened filling or other dental restoration piece is no longer possible, it has been necessary to deploy two light hardening devices in the dental practice so that, in the event of a failure of the first light hardening device or the reaching of the end of its operational availability, the second light hardening device could be deployed. In accordance with the present invention, the need to deploy two light hardening devices is now eliminated in that the LED arrangement has a drastically increased life cycle and a complete failure or falling out is, in practice, completely foreclosed. The reason for this lies in the fact that the multiple arrangement of LED chips ensures that if a single chip falls out or fails, the light output or performance is reduced by, for example, 5% and this reduction in light output can be compensated for by an increased hardening time.
It is to be understood that the number of LED chips can be accommodated to a wide range of requirements. In connection with round socket elements for the light guide rod, an arrangement of 5xc3x975 LED chips, for example, can be specified so that, in total, 25 chips are available or the corners chips can be omitted so that in total 21 chips are available. Preferably, the chips are arranged in the closest possible arrangement with one another and in immediate neighboring proximity to the entry of the light guide rod.
In accordance with the present invention, it is particularly advantageous that commercially available light guide devices need no further modification to be deployed as a light hardening apparatus or device in connection with the present invention, or to be provided with the light source of the present invention in substitution for the reflecting halogen glow lamp. In this manner, the cooling body preferably includes two electric contact rods or plug elements on its back end which correspond to the contact rods of a halogen glow lamp. The cooling process follows in the manner of a conventional halogen glow lamp cooling process by contact with the ribbed element bodies which encircle the halogen glow lamp. Preferably, the two ribbed element bodies are so firmly connected to one another as to ensure a secure arrangement so that the shedding or conducting away of the heat or warmth is assured.
Additionally, if a water cooling arrangement of the ribbed element bodies is to be factored in, so that the ribs are arranged in an overlapping aligned manner, it is preferable that an air cooling arrangement with a forced air element is provided which can thus lead to weight saving advantages.
It is additionally particularly advantageous that the temperature management of a commercially available light hardening device can be further used without modification. Typically, a forced air element or component is actuated as soon as the temperature exceeds a predetermined threshold value. Due to the improved working efficiency of the light source of the present invention, a reduced heat or thermal buildup occurs so that there is a corresponding prolongation of the time until the forced air element must be actuated.
The light hardening device and light source of the present invention are suitable as well for main voltage supply as well as for supply by means of a battery. Due to the substantially high working efficiency of the device for the light source, the life of the battery is extended.
In accordance with the present invention, it is particularly advantageous if the LED arrangement of chips is comprised of at least two different types of chips whose emission maximum are at different wave lengths. In this connection, the particular features of a two catalyzer system can be taken into account.
In an advantageous embodiment of the light hardening device of the present invention, it is further provided that the cooling body is configured in a hollow fashion and a control device is disposed in the interior of the cooling device for receiving thereon the LED chips. By a corresponding modification of the software or, alternatively, the hardware, of a hand device, it is also possible to sequentially actuate the two LED chip portions even if only two energy supply contacts are provided. In this connection, an impulse control can, for example, be provided, which is integrated with the control device disposed in the cooling body.
It is to be understood that any suitable desired modifications of the light hardening device or light source of the present invention are possible without going beyond the scope of the present invention. Thus, the cooling body can, as needed, also be configured as the base cooling body which can be connectable via corresponding adapters with the ribbed element bodies to ensure a good conducting away of the heat. It is also possible to improve the resistance to heat transfer between the cooling body and the ribbed element body by insertion of a conventional heat conducting paste.